Messages in this thread |  | | Date | Tue, 05 Jun 2001 11:11:06 -0400 | From | Brian Gerst <> | Subject | Re: meaning of vmalloc shortcut comment in fault.c |
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Bjorn Wesen wrote: > > Can someone elaborate on why it's bad to refer to tsk directly below (this > is a 2.4.5 change in x86) and why it's needed on x86 and not other archs.. > > What should I do for an arch that does not have a "cr3" machine register > to check with ?
%cr3 is the page table pointer on the x86. Changing the page table pointer and changing the stack pointer (from which tsk is derived) is not done atomically during a task switch. If an interrupt happens in between and causes a page fault on a vmalloced area, using tsk may refer to the wrong page tables. %cr3 by definition always has the current page table pointer.
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